Within the context of clinical trials, the section evaluates methodological issues relevant to both research and treatment, for example innovations in drug monitoring. In one study, sweat and urine specimens were collected from 44 methadone-maintenance patients to monitor cocaine use. Paired sweat patches that were applied and removed weekly (Tuesday) were compared to urine specimens collected Wednesday, Friday and Monday. Sweat patches were analyzed for cocaine, benzoylecgonine (BZE), and ecgonine methyl ester (EME); all patches (N=930) were analyzed by ELISA immunoassay (cutoff concentration 10 ng/ mL), and a subset of patches (N = 591) were also analyzed by GC-MS (cutoff concentration 5 ng/mL). Urine specimens were analyzed qualitatively for BZE by EMIT (cutoff 300 ng/mL), and a subset were also analyzed semiquantitatively for BZE by FPIA (LOD = 30 ng/mL) and quantitatively for cocaine by GC-MS (LOD = 5 ng/mL). Results were evaluated to: 1) determine the relative amounts of cocaine and its metabolites in sweat; 2) assess replicability in duplicate sweat patches; 3) compare ELISA and GC-MS results for cocaine in sweat; and 4) compare the detection of cocaine use by sweat and urine testing. Cocaine was detected by GC-MS in 99% of ELISA-positive sweat patches; median concentrations of cocaine, BZE, and EME were 393, 79, and 74 ng/mL. There was good replication of results in duplicate patches. The sensitivity, specificity, and efficiency of sweat ELISA cocaine results compared to sweat GC-MS results were 93.1%, 90.5%, and 93.5%. The sensitivity, specificity, and efficiency of sweat ELISA results for cocaine compared to urine EMIT results were 97.6%, 60.5%, and 77.7%. These findings support the utility of sweat patches for monitoring cocaine use, though further evaluation is needed. (Preston KL, Huestis MA, Wong CJ, Umbricht A, Goldberger BA, and Cone EJ. Monitoring cocaine use in sweat and urine of substance abuse treatment patients. Journal of Analytical Toxicology 23: 313-322, 1999.) - outcome predictor, cocaine, drug use monitoring, urinalysis, substance abuse, substance abuse treatment, sweat - Human Subjects